In part one, David Barker looked at how to decrease your data centre’s carbon footprint
through optimisation of air-conditioning and deploying new cooling technologies. In part two, he looks at how to optimise your electrical infrastructure and make the most of server virtualisation.
The environmental control systems will usually make up the largest proportion of a data centre’s energy usage (apart from the IT equipment itself), but that doesn’t mean there aren’t savings to be made elsewhere.
Two other areas to make direct and indirect energy savings are the building’s electrical infrastructure, along with the utilisation of the IT equipment, servers in particular.
Electrical infrastructure measures
If you’re responsible for the electrical infrastructure, then there are a few key areas that should be reviewed regularly to make sure you are getting the most efficient system possible.
- Replace your UPS: Older UPS systems, generally over five years old, won’t be as efficient as their modern counterparts. Transformer-less systems can now be supplied at 250KVa and, combined with other improvements, show significant gains in the power factor across the UPS. This means that more power is available for your servers while less is wasted within the UPS system.
- Look at power factor correction: If you are still using traditional cooling then you will probably have a large mechanical load in your data centre. This has the effect of introducing electrical ‘lag’ onto your supply. With power factor correction you remove this lag before it goes onto the grid, which not only avoids any power factor charges from your utility supplier, but also allows you to use more ‘real’ power (KW) for the same level of ‘apparent’ power (KVA).
- Install LED lighting: Replacing traditional fluorescent tubes with LED tubes has three advantages: an LED tube consumes around 70% less power than a fluorescent; it gives off a lot less heat (18 degrees for an LED tube versus 80-90 degrees for a fluorescent); and these lights are available with full spectrum or natural light, which is a lot easier to work in than the traditional yellow cast from a fluorescent.
- Check your cables: Data centre power cabling carries a lot of current to feed the power hungry IT systems. This current will create a magnetic field that can induce a voltage into the sheath of other cables running in parallel. This induced voltage can create circulating currents which will heat cables up and increase the amount of current within your power system.
To help reduce this, all single phase power cabling should be run in a trefoil formation with a cable for each phase of L1, L2 and L3. A trefoil formation is where all the cables are touching each other, making a triangle which keeps the distances between the cables to a minimum so the induced voltages are also minimised.
You can also introduce preventative measures to help identify circulating currents as well as undersized cables (which might be liable for failure), by performing a regular thermal imaging scan of your cabling to identify hot spots.
Server infrastructure savings
If you operate the server infrastructure in your data centre then you will probably be looking at some level of virtualisation within those servers.
This is essentially changing a server from being a single tenant, or single application machine (an analogy would be a house that just has one family living in it), into being a multi-tenant machine which has ‘virtual servers’ running inside it (to continue the analogy then the machine would become a block of flats with each flat being its own individual virtual server).
These virtual servers will appear to be full, dedicated machines to anyone who using them and they are normally limited in the resources they can use at any one time, so make sure you don’t have a single virtual machine monopolising all the processor or memory available.
Using the cloud
Another option is a cloud-based server infrastructure. It is worth remembering that cloud servers are essentially virtualisation-as-a-service, so you are basically paying for another company to take the work of running the physical hardware and virtualisation technology off your hands. Consider carefully, not just for the data security implications but also for financial, process and ownership issues which will vary from company to company.
Virtualisation isn’t for everyone, some applications don’t like virtual servers and need their own dedicated environments, but if you do go ahead with a programme of server virtualisation then the techniques and technologies (VMWare, Hyper-V, XEN, etc) need to be researched to find the solution that is most applicable to your needs. This isn’t a one size fits all solution and there are many different ways to implement a virtual server environment.
There are many avenues to reducing the carbon footprint of your data centre. Which route you go down will depend on how much control you have over the infrastructure on both the facility and server sides.
An enterprise data centre, which operates the facility as well as servers, has the most options available as it is able to tackle both the large cooling loads, as well as optimising server efficiency through virtualisation.
Posted by David Barker, founder and technical director at green colocation and connectivity supplier, 4D Data Centres
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